Field of the Invention
The invention relates to macroporous 3-D tissue engineering scaffolds comprising elastomeric cross-linked polymer units and interconnected macropores containing living cells.
Description of the Related Art
Methods for culturing cells in 3-dimensions (3D) have received growing attention in the field of tissue engineering, as the 3D approaches more closely mimic the microenvironment in which cells reside in vivo.[1-5] Extensive efforts have been dedicated towards developing 3D biomimetic scaffolds that incorporates biochemical, mechanical or architectural cues to facilitate desired cellular processes and tissue formation.[5-19] Hydrogels are a family of scaffolds widely used in tissue engineering applications due to its injectability, tissue-like water content, tunable biochemical properties, and ease for cell encapsulation.[5-11] However, most hydrogel-based scaffolds lack macroporosity (pore size larger than the size of cells), which may delay cell proliferation, migration, blood vessel ingrowth, or extracellular matrix (ECM) production.[20] Furthermore, hydrogel is often associated with weak mechanical strength, which limits their applications in engineering load-bearing tissues. Microfibers on the other hand, possess high mechanical strength and are frequently used as the building blocks to create highly porous scaffolds.[12-19] Microfibers can be bonded to form interconnected network that is inherently resilient to stress and deformation. Such network produces a large internal surface area that is amenable for modification to present biochemical cues. Microfiber-based scaffolds are typically macroporous, which provides ample 3D space that facilitates cell proliferation, migration and ECM production.
Various protocols have been developed to fabricate microfibers including macromolecule self-assembly,[12-13] micro-extrusion,[18-19] electro spinning,[14, 16-17] and template-assisted microfabrication.[15] Microfibers can then be bonded into a scaffold using solvent or chemical erosion,[15] solvent removal,[16-17, 19] or chemical crosslinking.[14, 18] However, these methods often involve the use of organic solvents, excess heat, high stress and harsh pH values, which are not cell-friendly. Therefore, cells can only be seeded onto microfiber scaffolds after the fabrication process, and left to grow into the microfiber scaffolds over time. Such processes often result in poor cell distribution and shallow cell penetration, which makes it difficult for applying microfibers to engineer tissues with clinically relevant dimensions.
Here we disclose crosslinkable hydrogels for fabricating macroporous and highly flexible tissue engineering scaffolds, and demonstrate their potential for supporting cell culture in 3D. The subject scaffolds combine the advantages from hydrogel and microfiber-based scaffolds, while overcoming the aforementioned limitations.
Non-woven fabrics (ex: U.S. Pat. No. 4,041,203, U.S. Pat. No. 5,188,885), electrospinning fibers (ex: U.S. Pat. No. 7,794,219), hydrogels for tissue engineering (ex: U.S. Pat. No. 7,854,923), wet-spinning method for making tissue engineering scaffolds (ex: U.S. Pat. No. 6,451,059).
Relevant art includes U.S. Pat. No. 8,017,107, U.S. Pat. No. 7,531,503, and U.S. Pat. No. 7,928,069.